This invention relates to electric discharge machines, and more particularly to automation of an electric discharge machine.
A conventional electric discharge machine is organized as shown in FIG. 5.
In FIG. 5, reference numeral 1 designates an electric discharge machining electrode; 2, a workpiece to be machined; 3, a machining vessel; and 4, a machining solution such as insulating oil in the machining vessel 3. Using the electric discharge machine, various machining operations are carried out with the workpiece 2 immersed in the machining solution in the machining vessel 3. With respect to FIG. 5, reference numeral 5 designates a pulse current generating unit for supplying an electric discharge pulse current to the electrode 1 and the workpiece 2; 8a indicates a ball screw for moving the main shaft of the electric discharge machine vertically (in a direction of Z-axis); 8c shows a ball screw for moving the workpiece 2 right and left (in a direction of X-axis); 9a indicates a servo motor for driving the ball screw 8a; 9b indicates a servo motor for driving a ball screw (not shown) which is adapted to move the workpiece 1 back and force (in a direction of Y-axis); 9c designates a servo motor for driving the ball screw 8c; and 10 designates a numerical control unit for suitably controlling the servo motors 9a, 9b and 9c according to a machining program. References numeral 11 designates a head member forming the upper portion of the electric discharge machine; 12 indicates a column which is a frame fixedly supporting the head member 11; 13 indicates a bed on which the electric discharge machine is installed; 14b indicates a movable table for moving the workpiece 2 and the machining vessel 3 back and forth (along the Y-axis); 14c, denotes a movable table for moving the workpiece 2 and the machining vessel 3 right and left (along the X-axis); 15, indicates a machining head mounted on the main shaft of the electric discharge machine; 16 designates an electrode exchanging unit for exchanging the electrode 1 on the main shaft; 17 denotes an arm for gripping an electrode during an electrode exchanging operation; and 18 indicates a magazine rack which accommodates a variety of tools such as electrodes 1.
The conventional electric discharge machine thus constructed operates as follows.
The electrode 1 and the workpiece 2 are confronted with each other while being held immersed in the machining solution in the machining vessel 3. Under this condition, a pulse current caused to flow between the electrode 1 and the workpiece 2 by the pulse current generating unit 5. As a result, electric discharge takes place between the electrode 1 and the workpiece 2 intermittently, thus machining the workpiece 2. During this operation, the electrode 1, being connected through the ball screw 8a to the Z- axis servo motor 9a, is moved up and down according to an instruction from the numerical control unit 10. As was described above, the Y-axis movable table 14b is connected through the ball screw (not shown) to the Y-axis servo motor 9b, and the X-axis movable table 14c is connected through the ball screw 8c to the X-axis servo motor 9c. These movable tables 14b and 14c are moved horizontally in response to instruction signals from the numerical control unit 10, so that the workpiece is positioned horizontally, or it is machined horizontally i.e., the workpiece 2 and the electrode 1 are moved relative to each other. Thus, by suitably controlling the operations of the servo motors 9a, 9b and 9c, a desired configuration can be formed in the workpiece at a desired position by electric discharge machining.
In the machining operation, the machining program and the machining conditions are determined by the operator according to the configurations of electrodes to be used and machining depths to be employed.
The conventional electric discharge machine thus constructed is disadvantageous in that electrical conditions must be determined separately according to the configurations of electrodes to be used, and therefore it is essential for the operator to refer to the configurations of electrodes to be used.